It helps people place this movie after X3. You'd be surprise (or not) that I still see people even on the Facebook movie page and twitter extremely confused as to when this movie takes place in the timeline. Also it's been said that Jean "pops up" in the movie "to mock, comfort and advise Logan" like "Number 6 in Battlestar Galactica" (Entertainment Weekly, May 31 issue). It implies some recurring screen presence.